Impact of Facial Fractures and Intracranial Injuries on Hospitalization Outcomes Following Firearm InjuriesFREE

1Department of Pediatric Critical Care, Case Western Reserve University School of Medicine, Cleveland, Ohio
2Department of Global Health, Harvard School of Dental Medicine, Boston, Massachusetts
3Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Massachusetts
4Texas A&M University Health Science Center, School of Rural Public Health, College Station, Texas
5Department of Orthodontics, College of Dentistry, The University of Iowa, Iowa City

ABSTRACT

ImportanceFirearm injuries (FAIs) play a major role in unintentional injuries, suicides, and homicides. It is important that policy makers, public health authorities, physicians, and the public are kept abreast of current trends in FAIs so that preventive programs can be tailored to the needs of cohorts that are at highest risk for such injuries.

ObjectivesTo provide nationally representative longitudinal estimates of outcomes associated with hospitalizations attributed to FAIs in all age groups in the United States during the years 2003 to 2010; to obtain prevalence estimates of skull and/or facial fractures and intracranial injuries among those hospitalized owing to firearm injuries; and to examine the association between the occurrence of skull and/or facial fractures and/or intracranial injuries and in-hospital mortality.

Design, Setting, and ParticipantsIn this retrospective analysis of the largest all-payer hospitalization data set in the United States, we evaluate a Nationwide Inpatient Sample of patients hospitalized for FAIs during the years 2003 to 2010.

Main Outcomes and MeasuresThe main outcome of interest was in-hospital mortality. The primary independent variables included occurrence of face and/or skull fracture and/or intracranial injuries.

ResultsDuring the study period, 252 181 visits were attributed to FAIs. Adolescents and young adults accounted for nearly 80% of all hospitalizations, with more than half of these in the 18- to 29-year-old, high-risk group. Male patients consistently accounted for 89% of the hospitalizations. The uninsured population accounted for nearly a third of hospitalizations. A total of 214 221 FAI hospitalizations did not involve facial and/or skull fractures or intracranial injuries; 13 090 involved a facial and/or skull fracture without a concomitant intracranial injury; 20 453 involved an intracranial injury without a concomitant facial and/or skull fracture; and 4417 involved both a facial and/or skull fracture and intracranial injury. Those with intracranial injuries without concomitant facial and/or skull fractures (odds ratio [OR], 58.40; 95% CI, 50.08-68.11) (P < .001) and those with both facial and/or skull fractures and intracranial injuries (OR, 17.45; 95% CI, 13.98-21.79) (P < .001) were associated with higher odds of in-hospital mortality than those without these injuries. Teaching hospitals were associated with higher odds of in-hospital mortality than nonteaching hospitals (OR, 1.31; 95% CI, 1.14-1.49) (P < .001). Teaching hospitals also tended to treat a higher proportion of complex cases. The uninsured had higher odds of in-hospital mortality than those with private insurance (OR, 1.55; 95% CI, 1.35-1.78).

Conclusions and RelevanceOccurrence of intracranial injuries was an independent risk factor for poor outcomes. Teaching hospitals had higher mortality rates but also treated more complex cases than nonteaching hospitals.

Firearm injuries (FAIs) play a major role in unintentional injuries, suicides, and homicides,1 which are the 3 leading causes of death among 15- to 34-year-olds2 in the United States. Years of life lost owing to unintentional injuries are substantial.3 Firearm injury has been perceived as a public health issue,4 and plans for firearm law reforms have been proposed.5 Estimates from the past decade show that about half of all self-inflicted FAIs and about 14% of FAIs associated with assaults result in head and neck injuries.6 Very few studies have reviewed FAIs resulting in head and neck injuries.7- 10 National estimates of the economic impact of FAIs are unclear. Furthermore, nationally representative estimates of prevalence and impact of facial and intracranial injuries on hospitalization outcomes following the use of firearms—unintentional, self-inflicted, or associated with assault—are lacking. It is important that policy makers, public health authorities, physicians, and the public are kept abreast of current trends in FAIs so that preventive programs can be tailored to the needs of cohorts that are at highest risk for such injuries. The objectives of the present study are to provide nationally representative longitudinal estimates of outcomes associated with hospitalizations attributed to FAIs in all age groups in the United States during the years 2003 to 2010; to obtain prevalence estimates of skull and/or facial fractures and intracranial injuries among those hospitalized owing to FAIs; and to examine the association between occurrence of skull and/or facial fractures and/or intracranial injuries and in-hospital mortality.

METHODS

Description of Database

The Nationwide Inpatient Sample (NIS) of the Healthcare Cost and Utilization Project for the years 2003-201011 was used.11 The NIS is the largest all-payer hospital-based inpatient database of the Healthcare Cost and Utilization Project (HCUP) sponsored by the Agency for Healthcare Research and Quality (AHRQ). The NIS is a stratified 20% sample of all acute-care hospitals in the United States. Each hospitalization in the NIS database is assigned a discharge weight that can be used to project all estimates and outcomes to nationally representative levels. We completed a data user agreement with HCUP-AHRQ and obtained the NIS data sets. The present study was exempt from institutional review board approval. Per the data user agreement, any individual table cell counts of 10 or lower cannot be presented to preserve patient confidentiality. In accordance with this data user agreement, such low cell counts are designated by the abbreviation DS, meaning discharge information suppressed.

Case Selection and Variables

All hospitalizations with an external cause of injury code (E-code) for FAI were selected for analysis. The E-codes used in the study are summarized in Table 1. Occurrence of skull and/or facial fractures and intracranial injuries were identified by the use of clinical classification software codes for these injuries in the primary and secondary diagnosis fields of the data set. The clinical classification software codes grouped together clusters of ICD-9-CM codes (International Classification of Diseases, Ninth Revision, Clinical Modification) that mapped to a set of diagnostic conditions.12,13 The presence of other bodily injuries including trauma-related joint disorders and/or dislocations, fracture of a femur, spinal cord injuries, fracture of an upper limb, fracture of a lower limb, other fractures, sprains and/or strains, crushing injury or internal injury, open wounds of the head and/or neck and/or trunk, and open wounds of extremities were also identified using clinical classification software codes. Demographic and hospital characteristics examined included age, sex, race, insurance status, hospital region, and hospital teaching status. Outcomes examined included disposition status following hospitalization for FAI, length of stay in the hospital, hospitalization charges, and in-hospital mortality. All hospitalization charges were adjusted to year 2010 US dollar values using the inflation rates for in-hospital care obtained from the Bureau of Labor Statistics.14

Analytical Approach

Descriptive statistics were used to examine the demographic characteristics. The association between patient demographics and/or types of injuries and/or hospital characteristics and in-hospital mortality was examined by a multivariable logistic regression model. Odds ratios (ORs) for different levels of independent variables and associated 95% CIs were computed. Each individual hospitalization was the unit of analysis, and NIS stratum was used as the stratification unit. Effects of clustering of outcomes within hospitals was adjusted in the regression model. All statistical tests were 2-sided and P < .05 was deemed to be statistically significant. All statistical analyses were conducted using SAS software, version 9.3 (SAS Institute) and SUDAAN software, version 10.0.1 (RTI International).

RESULTS

During the study period of over 8 years, 252 181 visits were attributed to FAIs. Adolescents and young adults accounted for nearly 80% of all hospitalizations, with more than half of these in the 18- to 29-year-old, high-risk group. Male patients consistently accounted for 89% of the hospitalizations. Black patients accounted for nearly half of the cases. The uninsured population accounted for nearly a third of hospitalizations. The characteristics of FAI hospitalizations by injuries are summarized in Table 2. A total of 214 221 FAI hospitalizations did not involve facial and/or skull fractures or intracranial injuries; 13 090 involved a facial and/or skull fracture without a concomitant intracranial injury; 20 453 involved an intracranial injury without a concomitant facial and/or skull fracture; and 4417 involved both a facial and/or skull fracture and intracranial injury. Overall, there were no differences in distribution of different age groups and sex groups by different types of fractures.

With regard to race, close to 50.6% of those with an FAI and no concomitant facial and/or skull fracture or intracranial injuries were black, while blacks made up only 44.1% of those with facial and/or skull fractures without concomitant intracranial injury, 31.4% of those with intracranial injury without concomitant facial and/or skull fracture, and 29.9% of those with both facial and/or skull fractures and intracranial injuries. A similar pattern was seen among the uninsured. About 34.5% of those with an FAI and no concomitant facial and/or skull fracture or intracranial injuries, 30.5% of those with facial and/or skull fracture without concomitant intracranial injury, 29.7% of those with intracranial injury without concomitant facial and/or skull fracture, and 26.6% of those with both facial and/or skull fractures and intracranial injuries were uninsured.

Other bodily injuries included trauma-related joint disorders and/or dislocations (n = 1222), fracture of the femur (n = 5055), spinal cord injuries (n = 9671), fracture of an upper limb (n = 37 841), fracture of a lower limb (n = 38 122), other fractures (n = 29 320), sprains and/or strains (n = 952), crushing injury or internal injury (n = 101 553), open wounds of the head and/or neck and/or trunk (n = 72 018), and open wounds of extremities (n = 81 729). Those with facial and/or skull fractures without concomitant intracranial injuries and those with both facial and/or skull fractures and intracranial injuries had a prevalence rate of 62.4% and 47.5%, respectively, of open wounds of the head and/or neck and/or trunk. Crushing injuries and/or internal injuries were present in 45% of those with no facial fractures or intracranial injuries and in 21.3% of those with facial and/or skull fractures without concomitant intracranial injuries. Overall, the number of hospitalizations owing to FAIs increased over the study period. The prevalence of facial and/or skull fractures and intracranial injuries also increased over the study period.

For all FAI-associated hospitalizations, assault by unspecified firearm was the most common cause of FAI, accounting for 36.8% of all FAI hospitalizations. Other frequently reported FAI causes included assault by handgun (18.9% of hospitalizations), accident caused by unspecified firearm missile (10.7%), accident by handgun (6.6%), injuries by firearms undetermined whether accidentally or purposely inflicted (5%), and assault by shotgun (4.1%). The different types of firearms attributed to FAI hospitalizations by injury type are summarized in Table 1. Among those who had FAIs involving facial and/or skull fracture without concomitant intracranial injury, the 3 most frequently reported causes were assault by unspecified firearms (36.0%), assault by handgun (22.0%), and accident caused by unspecified firearm missile (7.8%). Among those who had an intracranial injury without concomitant skull and/or facial fracture, the 3 most frequently reported causes were assault by unspecified firearms (26.7%), self-inflicted injury by handgun (18.8%), and self-inflicted injury by unspecified firearm (13.0%). Among those who had facial and/or skull fractures and intracranial injuries, the 3 most frequently reported causes were unspecified firearms (28.2%), self-inflicted injury by handgun (18.3%), and assault by handgun (12.9%).

Hospital characteristics by different types of injuries are summarized in Table 3. Overall, 79.2% of all FAI-associated hospitalizations were in teaching hospitals. Close to 86.4% of hospitalizations involving facial and/or skull fractures without concomitant intracranial injuries were in teaching hospitals, and 87.5% of those involving both facial and/or skull fractures and intracranial injuries were in teaching hospitals. Overall, 42.8% of all FAI-associated hospitalizations were located in the South. The trend of the South experiencing most FAI hospitalizations was similar for all types of injuries.

Following an FAI-associated hospitalization, a total of 20 355 people died in the hospitals in this study population (NIS hospitalizations) over the study period. The disposition status by injury type following FAI-associated hospitalization is summarized in Table 4. About 77.8% of those with an FAI and no concomitant facial and/or skull fracture or intracranial injuries, 71.2% of those with facial and/or skull fracture without concomitant intracranial injury, 24.7% of those with intracranial injury without concomitant facial and/or skull fracture, and 36.2% of those with both facial and/or skull fractures and intracranial injuries were discharged routinely following FAI hospitalization. The in-hospital mortality rate was the highest for those with intracranial injuries without concomitant facial and/or skull fracture (56.4% mortality rate). In-hospital mortality rates for those with both facial and/or skull fractures and intracranial injuries was 28.7%.

Overall hospitalization charges for the 8 study years (2003-2010) were close to $18.8 billion. Mean charges were $75 884/y. Mean length of stay varied from 6.3 to 7.6 days. Total length of stay over 8 years was about 1.7 million days. Length of stay and hospitalization charges by injury type are summarized in Table 5. Those with both facial and/or skull fractures and intracranial injuries had the highest mean hospitalization charges ($144 463) and mean length of stay (12.3 days).

Characteristics of hospitalization by teaching status of hospital are summarized in Table 7. Whites made up a lower proportion of cases treated in teaching hospitals (24.1%) than in nonteaching hospitals (40.2%). Medicaid patients made up 28.4% of cases treated at teaching hospitals (compared with 21.3% at nonteaching hospitals). A greater proportion of those with facial and/or skull fractures and/or intracranial injuries were treated in teaching hospitals than nonteaching hospitals. Overall, teaching hospitals treated cases with more other bodily injuries than nonteaching hospitals.

DISCUSSION

The present study used the largest all-payer in-hospital database to provide nationally representative estimates of hospitalizations associated with FAIs over an 8-year period from 2003 to 2010 in the United States. The prevalence estimates of facial and/or skull fractures and intracranial injuries in this cohort of patients and their impact on outcomes are examined. Results of the current study show that 252 181 hospitalizations were owing to FAIs, and about $18.8 billion hospitalization charges, 1.7 million hospitalization days, and 20 355 in-hospital deaths were attributed to FAIs. The years of life lost, disability, lack of productivity, societal well-being, and emotional turmoil associated with such injuries are far reaching and represent a significant “persistent” public health issue in the United States. Facial and/or skull fractures and intracranial injuries occur in close to 15% of FAI-associated hospitalizations. The present study estimates of prevalence of head and/or skull fractures are similar to earlier national estimates.1

Consistent with prior studies,8- 10,15 our results suggest that the occurrence of skull and/or facial fractures and intracranial injuries is associated with poor outcomes, high in-hospital mortality rates, and a substantial increase in hospitalization charges and length of stay in the hospital. In contrast to prior studies, our study estimates are generalizable and nationally representative and provide an overview of all types of FAI occurring across all types of community settings using the NIS database over an 8-year period from 2003 to 2010.

An interesting finding in our study is that the association of in-hospital mortality with FAIs was stronger among those with intracranial injuries without concomitant facial and/or skull fractures (OR, 58.40) than those with both facial and/or skull fractures and intracranial injuries (OR, 17.45). It is likely that a multitude of factors including severity of injuries, types of intracranial and facial and/or skull fracture combinations, other bodily injuries, and time of death may play a role in this pattern. The lack of more detailed clinical parameters in the NIS database precluded us from examining this pattern further. What is clear is that even after adjustment for all possible patient-related factors that were available in the database, those with intracranial injuries with or without facial and/or skull fractures had a higher risk for in-hospital mortality than those without intracranial injuries.

When we examined the trends in high-risk cohorts over the study period, we found that the same set of high-risk cohorts were consistently hospitalized owing to FAIs. Despite several educational preventive programs targeting high-risk groups over the past decade, the present study reveals perturbingly similar estimates of high-risk individuals who are likely to be hospitalized with FAI—adolescents, young adults, males, blacks, and the uninsured. Children with FAIs (intentional and unintentional) represent a population cohort that is not legally permitted to have access to firearms, which underlines the need to enforce and/or strengthen existing laws and highlight preventive interventions. Despite improvements in trauma care, length of stay and in-hospital mortality remained constant over the study period.

Results of the present study suggest that older age (≥41 years) was associated with significantly higher odds for in-hospital mortality than younger age. It is likely that older age groups have a higher comorbid burden that further complicates care and results in worse outcomes. However, this explanation needs further empirical support. The uninsured had significantly higher odds for in-hospital mortality than those covered by private insurance. It has been well established that lack of insurance is an independent risk factor for posttrauma mortality.16- 18 Prior studies have consistently shown that racial and/or ethnic minorities experience higher mortality rates following trauma than whites even after adjusting for several confounding factors.16,18 Contrary to this pattern, our study results suggest that even though blacks were the single largest racial group with FAI-associated hospitalizations, the adjusted in-hospital mortality rates for blacks were significantly lower than they were for whites. A possible explanation is that a greater proportion of the white study patients had an intracranial injury compared with blacks. A similar pattern was seen for Hispanics, who had a greater proportion of intracranial injury than blacks.

Teaching hospitals were associated with higher odds for in-hospital mortality than nonteaching hospitals. This finding is not surprising because teaching hospitals are more likely to treat high-risk cases and serve as tertiary centers where extremely sick patients are referred for further care. The greater severity of cases in teaching vs nonteaching hospitals could explain the greater in-hospital mortality rates in teaching hospitals.19 Comparison of patient characteristics between teaching and nonteaching hospitals in our study showed that teaching hospitals treated a greater proportion of blacks and Medicaid patients than did nonteaching hospitals. Also, teaching hospitals treated a greater proportion of those with multiple other bodily injuries. It is likely that the higher mortality rates seen in teaching hospitals were caused by the greater complexity of cases treated.

Our study also found a geographic variation in in-hospital mortality rates. Hospitals located in the Midwest and South tended to have significantly lower in-hospital mortality rates than those located in the West. A multitude of factors including type and severity of FAIs, patterns of care delivered, and small area variations might have contributed to these regional differences,20 and these should be further explored by future studies.

The estimates from this study should be interpreted in light of the inherent weaknesses of using hospital discharge data sets. The present study provided estimates of FAIs that resulted in a hospitalization. Those FAIs that resulted in instant death were not captured in the current data set and hence were not included in the analysis, nor were those patients with FAIs who were discharged from hospital-based emergency departments without subsequent hospitalization. Consequently, the economic and mortality estimates that are presented herein actually underestimate the true burden associated with FAIs. Considering the retrospective nature of the study, the cause-and-effect relationship between facial and/or skull and/or intracranial injuries and in-hospital mortality cannot be conclusively established. The present study found only an association. However, what is clear is that facial and/or skull and/or intracranial injuries are associated with poor outcomes.

The incremental effects of additional injuries were not established in the present study and should be the focus of future investigations. Furthermore, the severity of the intracranial injuries and skull and/or facial fractures was not examined in the present study because the ICD-9-CM codes indicate only the presence of injuries and not the severity of injuries. It is likely that severe injuries lead to adverse outcomes. The fact that severity was not adjusted in our analysis could confound some of our study findings. Even though the NIS database has been validated and has been extensively used for examining health resource utilization patterns in hospital settings, the effects of coding biases should not be discounted. As with any discharge data sets, there could be issues or errors with coding, and this could bias any estimates.

Finally, the multivariable regression model that was used in the current study was limited to the variables available in the NIS database. Behavioral attributes of patients are not captured. Consequently, the issue of omitted variables bias should be kept in view while interpreting the results from the multivariable regression model.

CONCLUSIONS

During the years 2003 to 2010, a total of 252 181 visits were attributed to FAIs. Close to 15% involved a fracture of face and/or skull and/or intracranial injuries. Occurrence of intracranial injuries was an independent risk factor for poor outcomes. Those who had an intracranial injury had significantly higher odds for in-hospital mortality than those who did not have an intracranial injury. Our conclusions should be interpreted in light of the limitations of large secondary discharge data sets. Future studies must examine the role of severity of intracranial and skull and/or facial fracture injuries on hospitalization outcomes.

Previous Presentation: Limited results from this research were presented as an oral presentation at the 141st American Public Health Association Annual Meeting; November 2-6, 2013; Boston, Massachusetts.

Centers for Disease Control and Prevention (CDC). Years of potential life lost from unintentional injuries among persons aged 0-19 years—United States, 2000-2009. MMWR Morb Mortal Wkly Rep. 2012;61(41):830-833.PubMed

Centers for Disease Control and Prevention (CDC). Years of potential life lost from unintentional injuries among persons aged 0-19 years—United States, 2000-2009. MMWR Morb Mortal Wkly Rep. 2012;61(41):830-833.PubMed

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